1. Field of the Invention
This invention relates generally to treatment of animal udders to prevent bacterial infection such as mastitis.
2. Description of the Prior Art
The concept of teat treatment to prevent mastitis by application of a physical barrier such as a film-forming polymer latex is old in the art as evidenced by the Andrews, et al. U.S. Pat. No. 4,113,854. The Andrews patent discloses a method for the prevention of mastitis in milk-producing animals in which the teats of the animal are dipped into a solution which is comprised of a film-forming polymer latex and a water soluble polymer thickening agent in an aqueous medium. In addition, the Andrews U.S. Pat. No. 4,113,854 in column 1, lines 43 to 63 describes the prior film-forming materials containing polyvinyl acetate and polyvinyl chloride or vegetable oils which Andrews found to either be ineffective or to produce irritation to the animal's teat.
Andrews states his solution should have a thioxotropic value of 15 to 1200 dynes/cm.sup.2 and a practical upper viscosity limit of 10 poise at a shear rate of 250/sec. Andrews suggests natural or synthetic water soluble polymers which include the modified polymers which are derivatives of cellulose. Andrews points out that cellulose is not water soluble without modification and states that typical cellulose derivatives include methyl, hydroxyethyl and sodium carboxymethyl cellulose derivatives and combinations thereof. Andrews also requires a polymer latex which has suitable film-forming characteristics. The latexes of styrene butadiene, acrylic polymers and acrylic copolymers. He states the preferred polymer latexes include ethyl acrylate/methyl methacrylate copolymers, methyl methacrylate/butyl acrylate copolymers and styrene butadiene copolymers. An especially preferred material of Andrews is an ethyl acrylate/methyl methacrylate copolymer.
In addition, Andrews suggests adding an antiseptic material such as alcohol, chlorohexidine, iodine, 8-hydroxy quinoline sulfate or sodium hypochlorite to his mixture.
Andrews contends that when the teat is dipped in the mixture, it forms a film around the animal's teat which provides a shield against bacterial infections such as mastitis.
One of the problems with the prior art teat coating is that although the Andrews patent describes such teat coating as water soluble, in practice it has been difficult to completely remove the film barriers on the teat with water which may result in plugging the milk line filters. The sales literature of Andrews' assignee, Minnesota Mining and Manufacturing Company, titled The Physical Barrier Against Mastitis, alludes to the problem of incomplete removal by stating "Teat shield will not dissolve in milk. Your filter will trap any entering the milk line."
While Andrews emphasizes the physical barrier aspect of a film formed by the combination of polymer latex and a water soluble thickening agent, he also suggests one could incorporate an antiseptic into the material. One of the problems is to provide a workable combination of film and antiseptic that do not react with each other. We have discovered that the combination of chlorohexidine (typically as the gluconate) and a water soluble cellulosic film-former, typically hydroxmethyl cellulose, provides a film that provides long lasting bacterial protection to an animal's teats.
One of the problems associated with prior art teat dips is that during storage the teat dip solution may freeze and separate. The present invention overcomes this problem by use of an alcohol solution which does not freeze under normal barn storage temperatures, e.g., temperatures down to minus 18.degree. C. or thereabouts, but below 0.degree. C. The alcohol readily evaporates when placed on the cow's teat to permit the film to rapidly form on the animal's teat.
Still other prior art is described in the Journal of American Veterinary Medical Association article of Farnsworth, Wyman and Hawkinson titled "Use of a Teat Sealer for Prevention of Intramammary Infections in Lactating Cows". This article describes the use of an acrylic latex film as a physical barrier which is removed by rubbing.
The prior art also shows the use of nonfilm-forming teat dips marketed under the trade name Tesan. The Tesan dip comprises a liquid solution and bactericide of chlorhexidine which is claimed to adhere to the animal's teats.
Another teat dip is described in the product bulletin of Lonze Technical Service Laboratories. Lonza's product uses chlorhexidine gluconate in combination with other ingredients. The Lonza product is also a nonfilm-forming coating.
Still other publications such as the Journal of Dairy Science lists a number of germicides for use in teat dip preparation.
The present invention comprises an improvement to the prior art teat dips by providing a film-forming liquid that is safe and can be completely removed with water.